marking pcb's

[CWatters]

Dallas Semiconductors (now owned by Maxim) used to make a part in small two
pin package that contained a unique 64 bit serial number (eg every one is
different). I think it was the DS2400 and they were intended for
applications like MAC addresses on NIC's.

One of these epoxied into a hole in the PCB would be impossible to remove
and replace without damage.

The nearest I could find on the Maxim web site now are these ibuttons which
are a bit too big I think but perhaps I didn't look hard enough.

http://www.maxim-ic.com/quick_view2.cfm/qv_pk/3711




"zapp" <zapp@nospam.com> wrote in message
news:i9UDb.7688$3B2.2449@bignews1.bellsouth.net...

Thanks for all the replies! Elaborating, these are identical
microcontroller boards with a perfboard wirewrap area. After some time
into
the semester, there will be many of hours of wirewrap work put into each
board. Hopefully, the identifying mark will prevent a student from
casually
using another's work.

Varnish can be dissolved, someone seemed to mention. Is epoxy insoluble?
Also, does it come in clear forms? Perhaps epoxy over a paper label or
engraving.

The digital camera may work, but there are several lab instructors.


Zapp



"DarkMatter" <DarkMatter@thebarattheendoftheuniverse.org> wrote in message
news:79gvtvkvbi4559j4sd7tcjukdbsl02tggk@4ax.com...
On Tue, 16 Dec 2003 7:01:17 -0800, DaveC <me@privacy.net> Gave us:

I suggest a digital photo of the PCBs, both sides. No s/n required.
Simply
compare the handed-in project to the photos you keep on file. 50
projects
is
a bit much, I realize, but I don't know any other way to be sure the
handed-in *design* is the student's own.


I'll bet that the PCBs are all the same, and the test is for
assembly skill as well as finished assy function.

 

[Philip Pemberton]

In message <ERWDb.82513$mN5.3166277@phobos.telenet-ops.be>
"CWatters" <colin.watters@pandoraBOX.be> wrote:

Dallas Semiconductors (now owned by Maxim) used to make a part in small two
pin package that contained a unique 64 bit serial number (eg every one is
different). I think it was the DS2400 and they were intended for
applications like MAC addresses on NIC's.
The original was the DS2400. The silicon designs have been tweaked by DalSemi

to fix a few glitches in the 1-Wire driver. The new part number (when I say
"new" I mean "since 1996-ish") is DS2401. ISTR there's even a Chipscale
version - solder some really tiny wire to it and embed it in hole on the
board. Add some Araldite and you've got a usable anti-tamper method. You'd
need a 1-Wire reader (a DS9097U and a Blue Dot Receptor) to read the codes,
though. Keep a database using Access or Excel (or whatever) - use the 1-Wire
Viewer to read the code off the chip, then look it up in your database.

Later.
--
Phil. | Acorn RiscPC600 Mk3, SA202, 64MB, 6GB,
philpem@despammed.com (valid address)| ViewFinder, 10BaseT Ethernet, 2-slice,
http://www.philpem.dsl.pipex.com/ | 48xCD, ARCINv6c IDE, SCSI
REALITY.SYS corrupted: reboot universe?

 

[Ross Mac]

"DarkMatter" <DarkMatter@thebarattheendoftheuniverse.org> wrote in message
news:h3gvtvgdqvkpefjq9t3f5r06a7bd6o28l5@4ax.com...

On Tue, 16 Dec 2003 10:36:47 GMT, "Ross Mac"
this.is.a.mung@example.invalid> Gave us:

Odds are each board is different...so artwork would not be a
problem....otherwise, break out the old engraver...that's the most common
way to track boards through a shop, other than cropping the corners I
suppose....


Wrong. Odds are.. each board is the same, and each student is being
tested on assembly process ability.
The post was a bit vague.....I don't see anywhere the claim that the boards

are the same......I guess you have insider info since you find it necesary
to correct.....
Though, you might be correct!!

 

[Ross Mac]

"DarkMatter" <DarkMatter@thebarattheendoftheuniverse.org> wrote in message
news:96gvtv0ps8hoa1rce8tjv52gooagrdl0hf@4ax.com...

On Tue, 16 Dec 2003 7:01:17 -0800, DaveC <me@privacy.net> Gave us:


A solution has not yet been suggested that meets these requirements.


Bullshit. My edge notch encoding scheme makes unique, all but
un-decodable (except by the instructor) PCB coding/serializations.
Only one problem....once you rout the board from it's frame...the notches

are gone.....I have seen this time and time again when engineers are running
tests.....You would have to notch the finished product....and most probably
make it seriously ugly.....

 

[DarkMatter]

On Wed, 17 Dec 2003 03:11:30 -0500, "zapp" <zapp@nospam.com> Gave us:

Varnish can be dissolved, someone seemed to mention. Is epoxy insoluble?
Also, does it come in clear forms? Perhaps epoxy over a paper label or
engraving.

Use the opaque epoxy as an ink. Make numerals. It can be scraped
off, but where do they get *YOUR* brand to remark it with?

Since the notches do not involve any actual numerals, but are
encoded by you with a limited set, they cannot decode them to copy or
falsify them.

 

[Ross Mac]

"zapp" <zapp@nospam.com> wrote in message
news:i9UDb.7688$3B2.2449@bignews1.bellsouth.net...

Thanks for all the replies! Elaborating, these are identical
microcontroller boards with a perfboard wirewrap area. After some time
into
the semester, there will be many of hours of wirewrap work put into each
board. Hopefully, the identifying mark will prevent a student from
casually
using another's work.

Varnish can be dissolved, someone seemed to mention. Is epoxy insoluble?
Also, does it come in clear forms? Perhaps epoxy over a paper label or
engraving.

The digital camera may work, but there are several lab instructors.


Zapp



"DarkMatter" <DarkMatter@thebarattheendoftheuniverse.org> wrote in message
news:79gvtvkvbi4559j4sd7tcjukdbsl02tggk@4ax.com...
On Tue, 16 Dec 2003 7:01:17 -0800, DaveC <me@privacy.net> Gave us:

I suggest a digital photo of the PCBs, both sides. No s/n required.
Simply
compare the handed-in project to the photos you keep on file. 50
projects
is
a bit much, I realize, but I don't know any other way to be sure the
handed-in *design* is the student's own.


I'll bet that the PCBs are all the same, and the test is for
assembly skill as well as finished assy function.


Now we know they are all the same!....here is an easy way to identify each

board....during the drilling process have a serial number drilled with one
of the smaller holes in a land area....there are M codes that allow you to
do this and it is a minimal engineering expense....it could be as easy as 1
to 50 ...they could easily do this for you...and hey, you can't forge that
now can you.....Just assign a number to each student.....You may have seen
card frames with lot numbers drilled into them...this is how some PCB houses
keep board lots from getting mixed during the plating process where most of
the "evils" occur.....
A happy holiday season to all.....Ross

 

[DarkMatter]

On Wed, 17 Dec 2003 11:11:32 GMT, "CWatters"
<colin.watters@pandoraBOX.be> Gave us:

Dallas Semiconductors (now owned by Maxim) used to make a part in small two
pin package that contained a unique 64 bit serial number (eg every one is
different). I think it was the DS2400 and they were intended for
applications like MAC addresses on NIC's.

One of these epoxied into a hole in the PCB would be impossible to remove
and replace without damage.

They also have some with RTCs in them. The startup time, and serial
cannot be duped, so hiding it physically is not required.

The nearest I could find on the Maxim web site now are these ibuttons which
are a bit too big I think but perhaps I didn't look hard enough.

There are RTC chips out there that are serialized.

http://www.xs4all.nl/~ganswijk/chipdir/f/rtc.htm

 

[DarkMatter]

On Thu, 18 Dec 2003 02:23:08 GMT, "Ross Mac"
<this.is.a.mung@example.invalid> Gave us:

The post was a bit vague.....I don't see anywhere the claim that the boards
are the same......I guess you have insider info since you find it necesary
to correct.....
Though, you might be correct!!

It was obvious to me. It was later confirmed by the instructor.

 

[DarkMatter]

On Thu, 18 Dec 2003 02:26:16 GMT, "Ross Mac"
<this.is.a.mung@example.invalid> Gave us:

"DarkMatter" <DarkMatter@thebarattheendoftheuniverse.org> wrote in message
news:96gvtv0ps8hoa1rce8tjv52gooagrdl0hf@4ax.com...
On Tue, 16 Dec 2003 7:01:17 -0800, DaveC <me@privacy.net> Gave us:


A solution has not yet been suggested that meets these requirements.


Bullshit. My edge notch encoding scheme makes unique, all but
un-decodable (except by the instructor) PCB coding/serializations.
Only one problem....once you rout the board from it's frame...the notches
are gone.....I have seen this time and time again when engineers are running
tests.....You would have to notch the finished product....and most probably
make it seriously ugly.....

I guess that you've never owned or used needle files.

Small triangular notch, less than a half mm deep. Almost any
encoding schema can be used, and one can even be made up.

All but crack proof. Colored fingernail polish can even be
introduced, and the finished work varnished over to seal it in.

Nice, pleasing to the eye view of the individual PCB encoding.

The boards are already built as far as the SMT reflow part goes, if
it is SMT at all. No frame involved. They are all already broken
out, and get worked on individually by the students.

Notches?... We need some stinkin' notches!...

Badges?... We don' need no stinkin' badges!...

 

[Ross Mac]

"DarkMatter" <DarkMatter@thebarattheendoftheuniverse.org> wrote in message
news:fk42uvg2b2pm03l8omhk078elu7b7es6rc@4ax.com...

On Thu, 18 Dec 2003 02:23:08 GMT, "Ross Mac"
this.is.a.mung@example.invalid> Gave us:

The post was a bit vague.....I don't see anywhere the claim that the
boards
are the same......I guess you have insider info since you find it
necesary
to correct.....
Though, you might be correct!!


It was obvious to me. It was later confirmed by the instructor.
Glad you're sportin' wood on this one.....He never stated it until late in

the post!

 

[DarkMatter]

On Thu, 18 Dec 2003 02:33:13 GMT, "Ross Mac"
<this.is.a.mung@example.invalid> Gave us:

Now we know they are all the same!....here is an easy way to identify each
board....during the drilling process have a serial number drilled with one
of the smaller holes in a land area....there are M codes that allow you to
do this and it is a minimal engineering expense....it could be as easy as 1
to 50 ...they could easily do this for you...and hey, you can't forge that
now can you.....Just assign a number to each student.....You may have seen
card frames with lot numbers drilled into them...this is how some PCB houses
keep board lots from getting mixed during the plating process where most of
the "evils" occur.....
A happy holiday season to all.....Ross

The boards are already made, and even if they weren't, they would

still have to all be the same for each PCB on the palletized "frame"

Going through all of that trouble is kaka. Hell, the easiest way
would be to have them laser marked after the PCB mfg part was
finished. 3 seconds per PCB... max.

Kee rimany!

 

[Ross Mac]

"DarkMatter" <DarkMatter@thebarattheendoftheuniverse.org> wrote in message
news:3652uvovf86crhlhb4263mmnun2d2v8bh6@4ax.com...

On Thu, 18 Dec 2003 02:33:13 GMT, "Ross Mac"
this.is.a.mung@example.invalid> Gave us:

Now we know they are all the same!....here is an easy way to identify
each
board....during the drilling process have a serial number drilled with
one
of the smaller holes in a land area....there are M codes that allow you
to
do this and it is a minimal engineering expense....it could be as easy as
1
to 50 ...they could easily do this for you...and hey, you can't forge
that
now can you.....Just assign a number to each student.....You may have
seen
card frames with lot numbers drilled into them...this is how some PCB
houses
keep board lots from getting mixed during the plating process where most
of
the "evils" occur.....
A happy holiday season to all.....Ross

The boards are already made, and even if they weren't, they would
still have to all be the same for each PCB on the palletized "frame"

Going through all of that trouble is kaka. Hell, the easiest way
would be to have them laser marked after the PCB mfg part was
finished. 3 seconds per PCB... max.

Kee rimany!
No trouble at all.....what is your experience in this field???

 

[Kevin G. Rhoads]

You could also use a simple scribe to scrawl serializations on
therm. n Put drop os varnish over it, and tell them that damaged
varnish or serial numbers results in a Grade "F".

What is then to prevent another student from sabotaging the
serial on others' boards?

 

[PJ]

"zapp" <zapp@nospam.com> wrote in message
newsZ7Db.11170$C24.9870@bignews5.bellsouth.net...

I need to mark around 50 student PCB's for a microprocessor design lab.
This is to make sure that no one is cheating by using someone else's PCB.
I
would like to engrave a number or initials. Anyone have any suggestions?

Zapp

Get yourself a invisable marking pen that shows up under UV light. They are
used for secrectly marking things for what ever purpose you have. Probably
available at your local office supply store....Paul

 

[DarkMatter]

On Thu, 18 Dec 2003 15:07:29 -0500, "Kevin G. Rhoads"
<Kevin.Rhoads@Dartmouth.edu> Gave us:

You could also use a simple scribe to scrawl serializations on
therm. n Put drop os varnish over it, and tell them that damaged
varnish or serial numbers results in a Grade "F".

What is then to prevent another student from sabotaging the
serial on others' boards?

The other students... and their guns. :-]

 

[DarkMatter]

On Thu, 18 Dec 2003 17:36:51 -0800, "PJ" <packrat_paul@hotmail.com>
Gave us:

Get yourself a invisable marking pen that shows up under UV light. They are
used for secrectly marking things for what ever purpose you have. Probably
available at your local office supply store....Paul

With as many UV sources in school labs, I'd think that it would get
found out.

 

[Michael A. Terrell]

PJ wrote:

"zapp" <zapp@nospam.com> wrote in message
newsZ7Db.11170$C24.9870@bignews5.bellsouth.net...
I need to mark around 50 student PCB's for a microprocessor design lab.
This is to make sure that no one is cheating by using someone else's PCB.
I
would like to engrave a number or initials. Anyone have any suggestions?

Zapp



Get yourself a invisable marking pen that shows up under UV light. They are
used for secrectly marking things for what ever purpose you have. Probably
available at your local office supply store....Paul

How are you going to keep it from washing away when the flux is
cleaned off the board?
--
7 days!


Michael A. Terrell
Central Florida

 

[Ross Mac]

"DarkMatter" <DarkMatter@thebarattheendoftheuniverse.org> wrote in message
news:4r42uv0uaf2u52o2k3q26o12hn02b9bf2c@4ax.com...

On Thu, 18 Dec 2003 02:26:16 GMT, "Ross Mac"
this.is.a.mung@example.invalid> Gave us:


"DarkMatter" <DarkMatter@thebarattheendoftheuniverse.org> wrote in
message
news:96gvtv0ps8hoa1rce8tjv52gooagrdl0hf@4ax.com...
On Tue, 16 Dec 2003 7:01:17 -0800, DaveC <me@privacy.net> Gave us:


A solution has not yet been suggested that meets these requirements.


Bullshit. My edge notch encoding scheme makes unique, all but
un-decodable (except by the instructor) PCB coding/serializations.
Only one problem....once you rout the board from it's frame...the notches
are gone.....I have seen this time and time again when engineers are
running
tests.....You would have to notch the finished product....and most
probably
make it seriously ugly.....

I guess that you've never owned or used needle files.

Small triangular notch, less than a half mm deep. Almost any
encoding schema can be used, and one can even be made up.

All but crack proof. Colored fingernail polish can even be
introduced, and the finished work varnished over to seal it in.

Nice, pleasing to the eye view of the individual PCB encoding.

The boards are already built as far as the SMT reflow part goes, if
it is SMT at all. No frame involved. They are all already broken
out, and get worked on individually by the students.

Notches?... We need some stinkin' notches!...

Nice snip job!
Badges?... We don' need no stinkin' badges!...